Sheet discharge tray and a multiple bin sorter equipped with the same

ABSTRACT

A sheet discharge tray for stacking discharged sheets has a detachable member detachably mounted to a main unit from which the sheets are discharged, and a fastening member, attached to the main unit, for fastening the detachable member to the main unit. By mounting the detachable member to the main unit, the tray is configured to link the detachable member and the fastening member, thereby increasing the structural rigidity of a multi-bin sorter. The sheet discharge tray ensures the rigidity of the apparatus, makes packaging work easier when shipping the product, has a compact structure, and is capable of protecting accessory parts such as a static electricity discharging member and sheet detecting members.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a sheet discharge tray and to amulti-bin sorter equipped with the same, and more particularly to asheet discharge tray for stacking discharged sheets and a multi-binsorter arranged with a plurality of sheet discharge trays in up and downdirections.

Conventionally, sorters that sequentially sort sheets, having dischargetrays or a plurality of bins for sequentially stacking by placing sheetsformed with characters and/or images by an image forming apparatus suchas a copier or printer thereupon, or a sheet discharge apparatus orsheet stacking apparatus, such as a mailbox that separates and storesuser print jobs to each bin are well known in the art. Discharge traysin these apparatuses are detachably equipped at sheet discharge outlets(on the apparatus body). An example of such technology is disclosed inJapanese Patent Publication No. 2002-249273.

Various reasons for providing a detachable discharge tray can be raised.For example, when an apparatus is equipped with a plurality of dischargetrays, and a high-capacity stacking function has priority over adischarge sheet sorting function that uses the plurality of trays, alower discharge tray for stacking a high volume of sheets (see theaforementioned Japanese Patent Publication No. 2002-249273) can beemployed by detaching one of the mid-positioned discharge trays. Anotherobject of detachable discharge trays is to make it easier to package theproduct when shipping, even if there is only one discharge tray. Stillfurther, detachably forming a discharge tray also makes it moreconvenient to remove discharged sheets if a problem occurs in dischargesheet conveyance. Detachable trays also make it easier to replace adamaged one or to perform other apparatus maintenance.

Also, Japanese Patent Publication No. 11-157722 discloses detachablyequipping a stacking tray for stacking originals on an automaticdocument feeder apparatus installed on a copier. This is different fromwhen sheets are output from the image forming apparatus described above.

Output sheets and/or originals become charged with static electricitywhen conveyed through and discharged from the apparatus. Thus, a staticelectricity discharging member is generally disposed near the dischargeoutlet of the apparatus to remove static electricity to improvedischarging precision and alignment of sheets on a discharge tray. Amechanism is employed in the sheet discharge apparatus and/or the sheetstacking apparatus mentioned above to detect a full state which is theupper limit for stacking output and stacked sheets. Either an arm or alever that touches a top surface of a sheet is used for such a detectingmechanism. Examples are disclosed in the Japanese Laid-open PatentPublications No. 2002-249273 and No. 8-259093.

However, when incorporating an accessory part, such as the staticelectricity discharging member, to the detachable discharge traysdescribed above, special consideration must be taken to provide extrashock absorbing material when shipping the product. This translates intothe disadvantages of a more complex packaging process and increasedcosts. Specifically, it is natural for special care to be taken whenpackaging the apparatus as a product to prevent it from being damagedwhen shipped, transported and installed. Generally, a minimum acceptablelimit of shock absorbing material is prepared for the discharge trays.Because extra consideration must be paid to the accessory parts, such asthe static electricity discharging member, packaging work becomes morecomplex, and again, that translates into cost increases.

It is also necessary to consider grounding, in other words continuity ofthe static electricity discharging member. If a static electricitydischarging member is arranged on a detachable discharge tray, it isnecessary for the discharge tray to have a structure for continuity, inaddition to the problems outlined above. This also adds to the increasein cost.

Furthermore, when a detecting mechanism uses an arm or a lever member asfor detection described above, the arm and/or lever projects outwardfrom the apparatus. Therefore, if a discharge tray is removed, there isthe potential for a user to carelessly touch these parts which couldcause a decrease in detecting accuracy. There is also the problem ofsuch projection inviting damage to itself.

Furthermore, a configuration that incorporates a portion of a dischargetray inside the apparatus, for example providing a detachable dischargetray structure that disengages hooks formed on both edges of thedischarge tray from engaging orifices formed in both inner side walls ofthe apparatus body, has the problem of not being able to increase therigidity of the apparatus itself.

An object of the present invention, therefore, is to provide a sheetdischarge tray that ensures the rigidity of the apparatus, makespackaging work easier when shipping the product, has a compactstructure, and is capable of protecting the accessory parts, such as astatic electricity discharging member and sheet detecting members.

Another object of the present invention is to provide a multi-bin sorterthat ensures the rigidity of the apparatus side, that makes packagingwork easier when shipping the product, and reduces distribution(packaging) costs, that has a compact structure and is capable ofprotecting accessory parts, such as a static electricity dischargingmember and sheet detecting members.

Further objects and advantages of the invention will be apparent fromthe following description of the invention.

SUMMARY OF THE INVENTION

To attain the aforementioned objects, a first aspect of the presentinvention is a discharge tray composed of a detachable member detachablymounted to a main unit and a fastening member fastened to the main unit,for a sheet discharge tray for stacking discharged sheets.

According to the first aspect of the present invention, a tray isseparated into a detachable member detachably mounted to the main unit,and a fastening member fastened to the main unit. By mounting orinstalling the detachable member to the main unit, the tray isconfigured to link the fastening member and the detachable member. Forthat reason, because the fastening member that composes the tray isfastened to the main unit, the rigidity of the main unit side isincreased, even if the tray is a detachable structure. Also, thefastening member can be packaged as one body with the main unit, and thedetachable member, which is comparatively smaller in size than theoverall tray itself, can be packaged separately. This makes packagingwork easier when shipping the product, and decreases the costsassociated with product distribution (packaging). Still further, in theevent that a problem should occur in sheet discharge conveyance whileoperating the main unit, the detachable member can be removed from themain unit to enable a user to access the inside of the main unit. Thismakes the work to remedy problems more efficient.

Also according to the first aspect of the present invention, staticelectricity discharging members are disposed on the bottom surface ofthe fastening member to remove static electricity that tends to becharged to discharging sheets. This allows the fastening member fastenedto the main unit to protect the static electricity discharging memberswhen transporting or shipping the product, and eliminates the need forgrounding work after product delivery.

By equipping the fastening member above a movable lever member of alever sensor composed of a movable lever member that touches a topsurface of discharged sheets, and a sensor member for detecting astacking amount of discharged sheets through the rotation of the movablelever member, it is possible for this fastening member to protect themovable lever member. Therefore, this configuration prevents reduceddetecting accuracy caused by damage during shipment or by carelesslytouching the part while a user is operating the main unit.

Also, if the fastening member is disposed above a weight member thatpushes discharging sheets downward paired with the movable lever memberin a width direction of discharging sheets, the fastening member canalso protect the weight member in the same way as the movable levermember. Therefore, this also prevents product damage that can occur atshipping and prevents negative effects on product functions which can becaused by careless user contact when handling the machine. Furthermore,if the fastening member has a plurality of ribs on its bottom surface toguide discharging sheets, sheet alignment will be improved and therigidity of the fastening member will also be ensured. If the detachablemember has a plurality of ribs that connect to the plurality of ribs ofthe fastening member, the rigidity of the detachable member will be alsoincreased, as well as the strength of the entire tray.

In order to attain the aforementioned objects, a second aspect of thepresent invention is the aforementioned tray composed by connecting thedetachable member detachably mounted to the main unit, and the fasteningmember fastened to the main unit, in a multi-bin sorter arranging aplurality of sheet discharge trays in up and down directions forstacking sheets discharged from sheet discharge outlets.

The second aspect attains the same effects as the first aspect of thepresent invention. Sheet discharge trays of the first aspect arearranged in plurality in up and down directions to have the notableeffects of facilitating packaging work when shipping the product andreducing the costs associated with product distribution (packaging).

According to the second aspect of the present invention, it is preferredthat the fastening member be configured as one body with an uprightsurface of the main unit formed with sheet discharge outlets, in orderto ensure rigidity and to make the system more compact. Also, thefastening member has static electricity discharging members on itsbottom surface for eliminating static electricity charged to dischargingsheets, and is integrally composed with the upright surface of the mainunit formed with sheet discharge outlets. It is preferred that thefastening member has a projecting shape to protect members positionedbelow, from above.

Furthermore, if the system is configured to include a movable lever,equipped near a sheet discharge outlet, that rotates to touch a topsurface of sheets stacked on a tray, a sensor for detecting the stackingstate of sheets stacked on the tray along with the rotation of themovable lever, and first preventing means in a direction opposite to thedirection of sheet conveyance for preventing sheets from being insertedto above the movable lever, the first preventing means prevents sheetsfrom being inserted to above the movable lever even if a user carelesslyinserts sheets into the tray from a direction opposite to the directionof sheet conveyance. Thus, sheets are unable to be above the movablelever, so the benefit is that mis-operations caused when sheets aredischarged to the tray from the sheet discharge outlet will not occur,the sheet stacking state is accurately detected, and any dischargeproblems of sheets discharged from the sheet discharge outlet will notoccur.

The first preventing means have rotatable plate-shaped members. Theplate-shaped members rotate freely within a predetermined angle in afirst rotating direction by being touched by sheets being dischargedfrom the sheet discharge outlet. In a second direction opposite to thefirst direction, where sheets touch plate-shaped members in a directionopposite to the direction of sheet discharge, it is acceptable toconfigure the members so that their tolerable rotating angle of thesecond direction is controlled to be smaller than the tolerable rotatingangle of the first angle. In this case, first preventing means haveplate-shaped members whose rotating ranges are controlled atpredetermined angles, and supporting members that pivotally support theplate-shaped members. Projections formed on ends of a rotating shaft ofthe plate-shaped members contact with a portion of the inner wall of thesupport member bearing to control the range of rotation of theplate-shaped members. Trays are obliquely arranged. The bottom ends ofthe plate-shaped members are preferred to be positioned above the sheetmaximum stacking amount detection position where the movable lever ispositioned when the maximum number of sheets is detected by the sensor,using the planar surface of the tray as a reference.

Furthermore, it is preferred that the plate-shaped members hang downwardsubstantially vertically under their own weight. In this state, in theevent that a user manually inserts sheets in a direction opposite to thedirection of sheet discharge, the ends of the inserted sheets contactthe plate-shaped members causing them to rotate from their substantiallyvertical hanging posture to the predetermined angle in the seconddirection where the rotation is controlled. This makes it possible toguide the ends of the inserted sheets toward the tray. It is alsoacceptable for the projections equipped at one end of the supportmembers to be positioned at predetermined positions inserted in concaveportions formed in the main unit wall surface for the first preventingmeans.

It is also acceptable to equip rotatable weight members near a sheetdischarge outlet for pushing sheets discharged from the sheet dischargeoutlet downward, and second preventing means in a space above a traydownstream in the direction of sheet transport of the weight members,for preventing the insertion of sheets to above the weight members, in adirection opposite to the direction of sheet discharge. The movablelever members and weight members have substantially the same shape, andit is acceptable to equip them in pairs in a direction that intersectsthe direction of sheet discharge. It is also acceptable for firstpreventing means and second preventing means to have substantially thesame shape.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external, perspective view of a multi-bin sorter that canapply the present invention, installed in an image forming apparatus.

FIG. 2 is a perspective view of a portion of the multi-bin sorteraccording to the present invention with a detachable member linked to afastening member installed in a main unit.

FIG. 3 is a perspective view of an area near a sheet discharge outlet ofthe multi-bin sorter.

FIG. 4 is a fragmentary perspective view from below the multi-binsorter.

FIG. 5 is a perspective view of the multi-bin sorter as seen from abovewith trays removed, and first and second preventing means installed.

FIG. 6 is a perspective view of the multi-bin sorter as seen from abovewith trays mounted, and the first and the second preventing meansinstalled.

FIGS. 7A, 7B, and 7C are perspective views of the first preventing andthe second preventing means of the multi-bin sorter, wherein FIG. 7Ashows a plate-shaped member hanging downward under its own weight in asubstantially vertical posture; FIG. 7B shows the plate-shaped memberrotated in a sheet discharge direction; and FIG. 7C shows theplate-shaped member rotated in a direction opposite to the sheetdischarge direction and stopped.

FIGS. 8A, 8B, and 8C are side views of the first preventing means andthe second preventing means, wherein FIG. 8A shows the state of FIG. 7A;FIG. 8B shows the state of FIG. 7B; and FIG. 8C shows the state of FIG.7C.

FIG. 9 is a fragmentary sectional view of the positional relationshipsbetween a movable lever and the plate-shaped member.

FIG. 10 is a fragmentary perspective view of the first preventing meansbeing installed to the multi-bin sorter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the multi-bin sorter according to the presentinvention are described below with reference to the accompanyingdrawings.

As shown in FIG. 1, the multi-bin sorter 10 of the present invention ismounted to a side of an image forming apparatus having faxing, copying,scanning and/or printer functions as the main unit.

The image forming apparatus 1 has an automatic document feeder unit(commonly known as an ADF) 2 for automatically conveying originals, onthe top portion of the apparatus. An image reading unit, not shown, forreading originals is arranged below the automatic document feeder 2. Forthat reason, the image reading unit can read originals using either oftwo methods. Specifically, this unit can read characters and imagesformed on an original while the original is conveyed by the automaticdocument feeder 2, or it can read characters and images formed on theoriginal placed in a stationary position on a platen, not shown. Thecover, such as a pressure plate 3, over the platen can be opened in anupward direction to allow the original to be placed stationary on theplaten.

A display unit 4 for displaying processes of the image forming apparatus1, and a UI panel 7 for issuing operating instructions to the imageforming apparatus 1 are arranged on the front side (the near side ofFIG. 1) of the image forming apparatus 1. A lock lever 5 that opens theinside of the image forming apparatus 1 is arranged on the top portionof a multi-bin sorter 10 of a top cover 6. The lock lever 5 isconfigured to be released when there has been a conveyance problem of asheet formed with an image, to solve the problem (by removing aso-called paper jam) by rotating the upper cover along with theautomatic document feeder 2, the pressure plate 3, the display unit 4,the UI unit 7, and the image reading unit mentioned above upward andaway from the multi-bin sorter 10, thereby exposing the inside of theapparatus, not shown.

The image forming apparatus 1 has an interface that connects to a PC viaa printer cable or network cable, not shown. This image formingapparatus 1 is used as a multi-functional device having a printingfunction for printing characters and images generated on the PC, afaxing function for sending and receiving character and image data readby an image reading unit connected to a telephone/communication line,and copying and scanning functions that can be used independent of a PC.

Discharge trays 11 a, 11 b, and 11 c are equipped along up and downdirections for stacking discharged sheets, on one side of the multi-binsorter 10. Each of the discharge trays 11 a, 11 b, and 11 c is installedat a slant having a predetermined angle.

It is possible to operate the UI 7 to select either the discharge tray11 a, 11 b, or 11 c as the destination tray (for stacking) of sheetsdischarged from the image forming apparatus 1, depending on the way theimage forming apparatus 1 is used. For example, if sheets are printed,they can be stacked on the discharge tray 11 a. The discharge tray 11 bcan be used for facsimiles, and the discharge tray 11 c can be used forcopies. In addition, these discharge trays can be used as mail binsorters (in a mailbox system) by sorting sheets differentiating eachdischarge tray to use for each user by selecting the discharge tray thatcorresponds to the user's needs. Of course, if the desired dischargetray is full of stacked sheets, the user can switch subsequent sheets tobe discharged and stacked in a different discharge tray.

As shown in FIG. 2, each of the discharge trays 11 a, 11 b and 11 c iscomposed of a detachable member 42 detachably mounted to the main unit41 of the multi-bin sorter 10 and a fastening member 43 fastened to themain unit 41. The fastening member 43 is formed as one body with theupright surface 48 of the main unit 41 formed with sheet dischargeoutlets 12 (12 a, 12 b, and 12 c), extending to both sides of themulti-bin sorter 10, and projecting outward from the image formingapparatus 1. The discharge trays 11 a, 11 b, and 11 c share the samestructure. Therefore, an explanation will focus on the connectingstructure of the uppermost discharge tray 11 a. Explanations on thedischarge tray 11 b and 11 c shall be omitted. Note that the upper andside portion coverings of the multi-bin sorter 10 have been omitted fromthe image of FIG. 2 to facilitate understanding of the internalconfiguration of the multi-bin sorter 10.

Cylindrical hooks 46 projecting outward to the outer sides (the mainunit 41 side) are formed at the upper corners of both side edges.Engaging holes 45 are formed in both side inner walls 44 on the mainunit 41 to engage these hooks 46. By inserting the hooks 46 of thedetachable member 42 to engage the engaging holes formed in the mainunit 41, the separated detachable member 42 and fastening member 43become connected, thereby configuring the discharge tray 11 a. At thistime, the tray trailing edge support portion 47, at substantially thecenter of the detachable member 42, having a predetermined widthpositioned at the leading edge in the direction of insertion shown inFIG. 2, is positioned to touch the bottom surface of the opposingfastening member 43.

To detach the detachable member 42 from the main unit 41 and separate itfrom the fastening member 43, one lifts the end opposite to the traytrailing edge support member 47 of the detachable member 42 to free thetray trailing edge support member 47 from its contact with the bottomsurface of the fastening member 43. Then, by pulling the detachablemember 42 out and upward at an angle, the hooks 46 of the detachablemember 42 can easily be detached from the engaging holes 45 formed inthe main unit 41.

Sheet discharge outlets 12 (12 a, 12 b, and 12 c) are formed in theupright surface 48 of the main unit 41 for discharging sheets from theimage forming apparatus 1 to the discharge trays 11 (11 a, 11 b, and 11c). Sheets discharged from the sheet discharge outlets 12 a, 12 b, and12 c are stacked on each of the discharge trays 11 a, 11 b, and 11 c.Note that according to this embodiment of the present invention, themaximum stacking amount for the uppermost discharge tray 11 a, whenusing A4 size sheets having a basic weight of 80 g/m² is approximately100 sheets. For the second and third level discharge trays 11 b, and 11c, the maximum stacking amounts are approximately 50 sheets, when usingA4 size sheets having basic weights of 80 g/m².

As a rule, the sheet discharge outlets 12 a, 12 b, and 12 c, and othermembers arranged in close proximity thereto share the sameconfiguration. However, a movable lever member 14 a and a weight member15 a, described in detail below, arranged in close proximity to thesheet discharge outlet 12 a are wider extending in the center direction(the direction intersecting the sheet discharge direction) of the sheetdischarge outlet 12 a than the movable lever members 14 b and 14 c andthe weight members 15 b and 15 c arranged in close proximity to thesheet discharge outlets 12 b and 12 c. Their shapes are different. Thereason for this is to support special sheets that have a narrow width,such as envelopes or post cards discharged based on the center of thedischarge outlet. For this reason, the following will explain membersnear the sheet discharge outlets 12 b. An explanation of the sheetdischarge outlets 12 a, and 12 c will be omitted.

As shown in FIG. 3, a freely moving, movable lever member 14 b thatfunctions in combination with a photo-interrupter 27, described below,is disposed near the sheet discharge outlet 12 b as a detecting leverthat touches the uppermost surface of a sheet discharged to thedischarge tray 11 b. The leading end of the movable lever member 14 bhas a bent shape. The movable lever member 14 b is arranged in aposition that intersects the sheet discharge direction. Specifically, itis positioned to be able to touch the portion near a corner of a sheetstacked on the discharge tray 11 b, in the width direction of adischarged sheet. As the number of sheets stacked on the discharge tray11 b increases, and reaches a predetermined number, the movable levermember 14 b touches the top surface of the uppermost stacked sheet. Whenthe predetermined sheet volume increases further, the movable levermember 14 b rotates to a position to detect the maximum sheet stackingcapacity (volume of sheets).

The weight member 15 b that pushes sheets discharged from the sheetdischarge outlets 12 b downward by touching their top surfaces, isdisposed as a pair to the movable lever member 14 b on the opposite side(on the opposite side of the position of the movable lever member 14 bin a direction intersecting the sheet discharge direction) thereof (themovable lever member and the weight member are a pair for the same sheetdischarge outlet), sandwiching the sheet discharge outlet 12 b. Theweight member 15 b is also rotatably disposed, like the movable levermember 14 b. Note that in this embodiment, the movable lever members 14b and 14 c, and the weight members 15 b and 15 c share the sameconfiguration.

In the same way as the movable lever member 14 b, the weight member 15 btouches the top surface of the uppermost stacked sheet when the numberof sheets stacked on the discharge tray 11 b increases to reach apredetermined volume. The weight member 15 b also employs a freelyrotating configuration so it continues rotating motion simultaneously tothe rotating motion of the movable lever member 14 b. The sheet pressingfunction of the weight member 15 b improves the alignment of sheetsstacked in the discharge tray. Note that in the same way as the weightmember 15 b, the movable lever member 14 b also has a function forpushing sheets being discharged in a downward direction.

Discharge rollers 51 rotatingly driven by a power source and a drivetransmission mechanism, not shown, are disposed at both sides of thesheet width direction on a shaft 22 at the sheet discharge outlets 12 b.Discharge rollers 52 are opposingly arranged under each of the dischargerollers 51 to sandwich and discharge sheets. Note that by arranging thedischarge rollers 52 in a sheet discharge direction side in thehorizontal direction with regard to the discharge rollers 51, dischargedsheets are discharged moving upward.

The movable lever member 14 b is fixed to the shaft 24. The shaft 24rotates freely as a rotating shaft. An arm 26 integrally formed with adouser plate 25 is fixed to the other end of the shaft 24. The movablelever member 14 b, the arm 26 and the douser plate 25 integrally rotate.Also, along with the rotating motion of the movable lever member 14 b(as well as for the douser plate 25 and the arm 26), the douser plate 25advances into and interrupts the light path of a photo-interrupter 27equipped with light emitting and receiving elements that detects thestacked state of sheets stacked on the discharge tray 11 b.

To describe this element in more detail, according to this embodiment ofthe present invention, a slit 25 a is formed in the douser plate 25.Each time a sheet is discharged, the sheet raises the movable levermember 14 b (as well as the weight member 15 b). This causes the douserplate 25 to rotate and rise in synchronization as it advances into thelight path of the photo-interrupter 27. The part travels from itsinitial, transmissive state (a), to an interrupting state (b) (thedouser plate higher than the slit 25 a interrupts the photo-interrupter27), a transmissive state (c) (the photo-interrupter 27 is passingthrough the slit 25 a), and an interrupting state (d) (the douser plate25 is lower than the slit 25 a interrupting the photo-interrupter).During sheet discharge, the interrupted state of (d) is continued, butwhen sheet discharge is completed, the movable lever member 14 b (aswell as the weight member 15 b) is freed from pressing sheets and falls,thereby rotating the douser plate 25 downward. The slit 25 a of thedouser plate 25 moves from the interrupting state (d) to thetransmissive state (c) to the interrupting state (b), and to thetransmissive state (a) again, to return to its original status. Notethat when the volume of sheets stacked on the discharge tray 11 b hasreached a full state, in other words, the maximum amount that the traycan stack, the return motion (the motion of rotating downward) of thedouser plate 25 stops at the interrupting state (b). A controlmechanism, not shown, determines that the tray has reached its full, ormaximum stacking amount.

As shown in FIG. 3, the weight member 15 b is fixed to the shaft 28. Theshaft 28 rotates freely as a rotating shaft. Note that a gear 29 isdisposed on one end of the drive shaft 22 as the rotating shaft of thedischarge rollers 51. Drive from another gear, not shown, meshes withthe gear 29 from above to transmit drive and rotatingly drive the shaft22. Therefore, the shaft 22 and shaft 28 are connected.

As shown in FIG. 2, the fastening member 43 is disposed at a position toprotect the movable lever member 14 b and weight member 15 b. In otherwords, the fastening member 43 that configures a part of the dischargetray 11 a protects the movable lever member 14 b and weight member 15 b.The fastening member 43 that configures a part of the discharge tray 11b protects the movable lever member 14 c and weight member 15 c. (SeeFIG. 4.) According to this embodiment of the present invention, the gapbetween the discharge trays 11 is narrow at less than 40 mm. Because thedischarge trays 11 are disposed at an angle, it is difficult to lookinside. This has been considered from a technical standpoint. Note thatbecause there is no other discharge tray above the discharge tray 11 a,it is easier to view inside there. Therefore, a simple plate-shapedmember projecting from the upright surface of the main unit 41 protectsthe movable lever member 14 a and weight member 15 a.

Note that according to this embodiment of the present invention, each ofthe detachable members 42 and fastening members 43 that configure thedischarge trays 11 (11 a, 11 b, and 11 c) has convex and concaveportions. The convex portion of the fastening members 43 is equippedprojecting from the sheet discharge outlets 12 to protect the movablelever member 14 b and weight member 15 b equipped therebelow, fromabove. When the detachable member 42 is installed to the main unit 41,each part (namely the detachable member 42 and the fastening member 43)has a configuration for connecting. Specifically, the concave portion ofthe detachable member 42 engages the convex portion of the fasteningmember 43, and the convex portion of the detachable member 42 engagesthe concave portion of the fastening member 43. However, it is alsoperfectly acceptable to configure the discharge trays 11 to connect thedetachable member 42 and the fastening member 43 by forming them to beflat, and not have these concave and convex portions.

As can be seen in FIGS. 2 and 3, static electricity discharge brushes 13(13C is shown in FIG. 3) are equipped at the bottom (the under surface)of the fastening member 43 as static electricity discharging members forremoving static electricity charged to sheets, by touching the sheetbeing discharged from the sheet discharge outlets 12. In other words,the bottom (the under surface) of the fastening member 43 composes astatic electricity discharge brush (static electricity dischargingmember) mounting portion. As is clear from the drawings, the staticelectricity discharge brushes 13 b are mounted to the bottom of thefastening member 43 that configures the discharge tray 11 a. The staticelectricity discharge brushes 13 c are mounted to the bottom of thedischarge tray 11 b. (Also see FIG. 3.) Note that FIG. 3 schematicallyshows the static electricity discharge brushes 13 c.

As shown in FIG. 2, a plurality of ribs 49 are formed on the topsurfaces of the detachable member 42 and the fastening member 43 thatcompose the discharge trays 11 (11 a, 11 b, and 11 c) to improve thealignment of sheets discharged to and stacked on the trays. Some ofthese are disposed so that they are connected (continuous) having aslight gap when the detachable member 42 is mounted to the main unit 41.(Also see the discharge tray 11 b of FIG. 4.) FIG. 4 shows the bottomsurface of the discharge tray 11 b that is positioned in the middle, andthe configuration near the sheet discharge outlet 12 c that dischargessheets to the bottommost positioned discharge tray 11 c. According tothis embodiment of the present invention, three discharge trays (threebins) 11 a, 11 b, and 11 c are provided. The top surfaces of sheetsdischarged from the sheet discharge outlet 12 c that discharges sheetsto the lowest-positioned discharge tray 11 c via the discharge roller 52opposingly positioned to the discharge roller 51 rotatingly driven bydrive force from a drive mechanism, not shown, touch the plurality ofribs 54 on the bottom surface of the detachable member 42 of thedischarge tray 11 b positioned thereabove. While being discharged fromthe sheet discharge outlets 12 c the sheets are removed of staticelectricity by the static electricity discharge brushes 13.

However, if a sheet has a pronounced upward curl, the sheet pushes thestatic electricity discharge brushes 13 c upward while being conveyedforward in contact with the static electricity discharge brushes 13 c tothe plurality of ribs 53 equipped on the bottom surface of the fasteningmember 43 of the discharge tray 11 b. In this way, the plurality of ribs53 equipped on the bottom surface of the fastening member 43 function toguide a discharging sheet while indirectly (interposed by the staticelectricity discharge brushes 13) supporting the sheet, when discharginga sheet having a pronounced upward curl. Then, while the top surface ofthe sheet touches the plurality of ribs 54 and 55 equipped on the bottomsurface of the detachable member 42 of the discharge tray 11 b, thesheet falls and is collected on the lower discharge tray 11 c, beingguided by the ribs 54 and 55.

In this way, the ribs 53 (disposed on the bottom surface of thefastening member 43), and the ribs 54 and 55 (both disposed on thebottom surface of the detachable member 42) hold the posture of thedischarging sheet properly and have a utility in guiding dischargingsheets to the discharge tray 11 c. Also, as is clear in the drawings,portions of the ribs 53 on the fastening member 43 side and the ribs 54on the detachable member 42 side are disposed to connect with a slightgap when the detachable member 42 is installed to the main unit 41 andconnected to the fastening member 43.

Note that a fastening member 56 shown in FIG. 4 as a portion of thedischarge tray 11 c positioned at the lowermost position is configuredas a bottom portion of the multi-bin sorter 10 and is shaped forstability when the tray is installed on the apparatus.

Furthermore, on the multi-bin sorter 10, as shown in FIGS. 5 and 6,first preventing means 16 a and 16 b are equipped for preventing sheets(bundles) from advancing (being inserted) to above the movable levermembers 14 b and 14 c and allowing careless human contact with themovable lever members 14 b and 14 c. Even if a user inadvertently,manually inserts sheets (or a sheet bundle) into the discharge trays 11b and 11 c in a direction opposite to the sheet discharging direction,the first preventing means 16 a and 16 b are established at a downstreamside in the direction of sheet discharge of the movable lever members 14b and 14 c, so they protect these movable lever members. According tothis embodiment of the present invention, the gap between the dischargetrays is narrow at less than 40 mm and the trays are long, so it isdifficult to look inside. This has been considered from a technicalstandpoint. Note that the uppermost positioned discharge tray 11 a canstack twice the amount of sheets of the other trays 11 b and 11 c. Also,there is no other tray above the discharge tray 11 a, so it is easy toview inside, so there are no first preventing means established for themovable lever member 14 a.

Second preventing means 17 a and 17 b are equipped in a space above thedischarge trays 11 b and 11 c, for preventing sheets (bundles) fromadvancing (being inserted) to above the weight members 15 b and 15 c andallowing careless human contact with the weight members 15 b and 15 c.Again, even if a user inadvertently, manually inserts sheets to thedischarge trays 11 b and 11 c from a direction opposite to the sheetdischarging direction, in the same way as the first preventing means 16a and 16 b, the second preventing means 17 a and 17 b are established ata downstream side in the direction of sheet discharge of the weightmembers 15 b and 15 c and protect the weight members 15 b and 15 c. Thesecond preventing means 17 a and 17 b share the same configuration andthe same shape as the first preventing means 16 a and 16 b. Therelationships of the movable lever member 14 b and weight member 15 bare the same. The first preventing means 16 and the second preventingmeans 17 are disposed at the same discharge outlets in pairs (firstpreventing means 16 a is paired with the second preventing means 17 a,and the first preventing means 16 b is paired with the second preventingmeans 17 b) in the width direction of discharging sheets. Furthermore,according to this embodiment of the present invention, the firstpreventing means 16 a and 16 b, and the second preventing means 17 a and17 b all share the same configuration. Note that the uppermostpositioned tray la is not equipped with second preventing means for theweight member 15 a. Additionally, FIG. 3 that shows the configuration ofthe multi-bin sorter 10 near the sheet discharge outlet 12 b does notshow the first preventing means 16 a and 16 b, and the second preventingmeans 17 a and 17 b. (Neither does FIG. 4.) As shown in FIGS. 7A to 7C,and in FIGS. 8A to 8C, the first preventing means 16 a and 16 b (as wellas the second preventing means 17 a and 17 b) have plate-shaped members32 comprising a rotating shaft 31 and a hollow support member 33 thatpivotally supports the rotating shaft 31. A projection 34, substantiallyfan-shaped in cross-section, is formed on one end of the rotating shaft31. A convex control portion 35 is equipped on a portion of a bearinginner wall of the support member 33 to control the range of the rotationof the projection 34. Also, a projection 36 is disposed on one end ofthe support member 33. This projection 36 is inserted into the mainunit, as described below (see FIG. 10), to position the first preventingmeans 16 (particularly the plate-shaped member 32) at a predeterminedposition in the space above the tray 11, downstream of the sheetdischarge direction of the movable lever member 14 b.

With the configuration described above, the plate-shaped member 32 canfreely rotate within a predetermined angle around the rotating shaft 31pivotally supported by the support member 33. However, when theplate-shaped member 32 exceeds the predetermined angle, the projection34 of the plate-shaped member 32 side touches the control portion 35 ofthe support member 33 side to control and stop the rotating action.

FIGS. 7A to 7C and FIG. 8A to 8C each show the same status. FIGS. 7A and8A show the first preventing means 16 (projection 36) at the initialstate inserted into the machine side of the apparatus and theplate-shaped member 32 hanging downward substantially vertically by itsown weight.

FIGS. 7B and 8B show the plate-shaped member 32 being lifted by adischarging sheet in the direction of an arrow F (a first direction).These show the plate-shaped member 32 rotating from the state shown inFIGS. 7A and 8A. This rotated state continues while sheets are beingdischarged. Note that when the trailing edge of a discharging sheet iscompletely discharged from the sheet discharge outlet, the plate-shapedmember 32 is freed from its contact with the sheet and allowed to returnto the state shown in FIGS. 7A and 8A, by rotating in the oppositedirection of the first direction under its own weight.

FIGS. 7C and 8C show the projection 34 of the plate-shaped member 32touching the control portion 35 of the support member 33. This actioneffectively controls and stops the rotation of the plate-shaped member32. Specifically, this action occurs if the leading ends of sheets or asheet bundle touches the plate-shaped member 32 when a user removessheets or a sheet bundle from the top of the tray, and returns thesheets or sheet bundle back to the tray. If sheets or a sheet bundle ismanually reinserted in a direction of arrow R, a reverse direction ofthe sheet discharge direction (a second direction) from the sheetdischarge outlet (the direction of arrow F in FIGS. 7B and 8B), theplate-shaped member 32 rotates from a substantially vertical hangingposture, shown in FIGS. 7A and 8A, and rotates in an opposite directionof the rotating direction of the plate-shaped member 32 shown in FIGS.7B and 8B. In this state, the plate-shaped member 32 is positionedobliquely. This guides the leading ends of sheets or a sheet bundlebeing returned to the tray, toward the tray positioned below. Also, whenthe contact of the leading ends of the sheets or sheet bundle beingreturned to the tray is released from the plate-shaped member 32, theplate-shaped member 32 rotates in the opposite direction under its ownweight to return to the states shown in FIGS. 7A and 8A.

According to this embodiment of the present invention, the plate-shapedmember 32 is configured to be able to freely rotate within an angle of130°. As shown in FIGS. 7A and 8A, the plate-shaped member 32 uses thehanging state as a reference (0°). As shown in FIGS. 7C and 8C, therotating angle for the plate-shaped member 32 to rotate in the directionof the arrow R (a second direction), is set by the relationship of theprojection 34 and control portion 35 so that it is smaller than therotating angle allowed for the plate-shaped member 32 to rotate in thedirection of the arrow F (the first direction) in the direction of sheetdischarge, shown in FIGS. 7B and 8B.

As described above, sheets discharged from the sheet discharge outlet 12by the discharge rollers 21 (also the discharge roller 51) and dischargeroller 23 (also the discharge roller 52) are stacked sequentially on thedischarge tray 11. (Stacked sheets are omitted from the drawings.) FIG.9 shows the movable lever member 14 using a sensor, not shown, (thephoto-interrupter 27 in FIG. 3) that touches the top surface of theuppermost sheets of sheets stacked on the tray 11 to detect a full statewhich is the maximum stacking capacity of the tray. In this state, thebottom end of the plate-shaped member 32 of the first preventing means16 is disposed to be positioned higher than the sheet maximum stackingamount detection position (the position depicted in FIG. 9) where themovable lever member 14 is positioned, using the plane of the obliquelydisposed tray 11 as a reference.

Specifically, the bottom end position of the plate-shaped member 32 ofthe first preventing means 16 is positioned slightly above the lowestpoint position of the movable lever member 14 that touches the topsurface of the uppermost sheet. To make this easier to understand, FIG.9 includes dotted lines that delineate the lowest point position of themovable lever member 14 that touches the top surface of the uppermostsheet and the bottom end position of the plate-shaped member 32 of thefirst preventing means 16 in parallel with the plane of the tray 11.Note that the mounting height positions of the second preventing means17 are the same as the first preventing means 16.

As shown in FIG. 10, the projection 36 established on an end of thesupport member 33 of the first preventing means 16 mates with the systemby being inserted into a concave portion 39 formed in a portion of theapparatus wall surface 38, above the sheet discharge outlet 12 therebypositioning the first preventing means 16. This configuration positionsthe first preventing means 16 (particularly, the plate-shaped member 32)at a predetermined position in a space above the tray 11, downstream inthe direction of sheet discharge of the movable lever member 14. Notethat the mounting configuration of the second preventing means 17 to themain unit is exactly the same.

The following will explain the action of the multi-bin sorter 10according to this embodiment of the present invention.

The discharge trays 11 (11 a, 11 b, and 11 c) of the multi-bin sorter 10of this embodiment of the present invention are separated into thedetachable member 42 that is detachably mounted to a main unit 41, andthe fastening member 43 fastened to an upright surface 48 of the mainunit 41. By installing the detachable member 42 to the main unit 41, thefastening member 43 and the detachable member 42 are connected, therebyconfiguring a tray. For that reason, because the fastening member 43that configures the discharge tray 11 is fastened to the apparatus body,the rigidity of the multi-bin sorter 10 is increased even if thedischarge tray 11 is detachably configured. A portion of the dischargetrays 11 is positioned inside the main unit, in other words, thisincreases the rigidity of the device that has the projecting portion.Also, the fastening member 43 can be packaged with the multi-bin sorter10 and the detachable member 42 which is comparatively smaller than thedischarge trays 11 can be packaged separately, so packaging work whenshipping the multi-bin sorter 10 product is simpler, and the costsassociated with distribution (packaging) are reduced. Furthermore, whenperforming maintenance, for a problem, such as when a sheet dischargejam occurs during operation of the multi-bin sorter 10, the multi-binsorter 10 can be accessed by removing the detachable member 42 from themain unit 41, so the work to solve such problems is more efficient.

With the multi-bin sorter 10 of this embodiment of the presentinvention, static electricity discharge brushes 13 are disposed on thebottom (under side) of the fastening member 43, so the staticelectricity discharge brushes 13 are protected by the fastening member43 fastened to the main unit 41 when shipping the multi-bin sorter 10,and there is no need to ground the device after product delivery.

Still further, with the multi-bin sorter 10 according to this embodimentof the present invention, because a fastening member 43 is equippedabove the movable lever member 14 of the lever sensor composed of themovable lever member 14 that touches the top surface of dischargingsheets, and the sensor members of the shaft 24, the douser plate 25, thearm 26 and the photo-interrupter 27 that detect the stacking amount ofsheets with the rotation of this movable lever member 14, the movablelever member 14 is protected by the fastening member 43. Therefore, thisprevents damage when the product is shipped, and it prevents degradeddetection accuracy cause by carelessly coming into contact withsomething when the machine is used. Also, because a fastening member 43is disposed above the weight members 15 that push discharging sheetsdownward, equipped to be a pair with the movable lever member 14 b inthe width direction of discharging sheets, the fastening member 43 alsoprotects the weight member 15 in the same way as the movable levermember 14. Therefore, this also prevents damage when shipping theproduct and prevents reduced function cause by careless contact whenusing the machine.

With the multi-bin sorter 10 of this embodiment of the presentinvention, the fastening member 43 has on its bottom surface a pluralityof ribs 53 that guide discharging sheets, as described above. Thisfeature increases sheet alignment and ensures the rigidity of thefastening member 43. The detachable member 42 has a plurality of ribs 54and 55 that link with the plurality of ribs 53 of the fastening member43 when mounted to the main unit 41. Therefore, discharging sheetsmaintain a good posture, and this configuration enhances the rigidity ofthe detachable member 42, and strengthens the overall discharge trays11.

Also, with the multi-bin sorter 10 of this embodiment of the presentinvention, the top surface of discharged sheets from a sheet dischargeoutlet 12 touches the movable lever member 14. This rotates the movablelever member 14, and along with that rotation, the detecting mechanismcomposed of the shaft 24, the arm 26, the douser plate 25, and thephoto-interrupter 27 detect the state of stacked sheets. In other words,the detecting mechanism detects the stacking status of single sheetsdischarged from a sheet discharge outlet 12. Also, a control mechanism,not shown, determines the full status, which is the maximum stackingamount of sheets, when the return operation of the douser plate 25 isstopped at the light interrupting state of (b), as described above.Therefore, the multi-bin sorter 10 has a detecting mechanism fordetecting one sheet at a time stacked on the discharge tray 11 from asheet discharge outlet. This accurately detects the stacking state ofsheets on the discharge tray 11, and a full state of the discharge tray.

The multi-bin sorter 10 of this embodiment of the present invention hasfirst preventing means 16 a and 16 b equipped at a downstream side inthe direction of sheet discharge of the movable lever members 14 b and14 c, and in the space above the trays 11 b and 11 c. The firstpreventing means 16 a and 16 b prevent sheets (a bundle) from becominginserted to above the movable lever members 14 b and 14 c, even when auser removes sheets (a bundle) once and returns them back to top of thetrays 11 b and 11 c in the reverse direction of sheet discharge. Withconventional multi-bin sorters, if sheets (or a bundle) whose edges arecurled are re-inserted into the tray, the curled end of the sheets willbe caught in the upper side of the detection lever for detecting thestacking amount of sheets stacked on the tray and cause mis-detectionswhen detecting the sheet stacking amount. Thereafter, sheet dischargeproblems can occur, and if the sheets are forcefully returned, there isthe possibility of damaging the detection lever. To solve those issues,the multi-bin sorter 10 uses the first preventing means 16 a and 16 bprevent sheets from entering above the movable lever members 14 a and 14b, even if sheets are carelessly re-inserted into a tray from adirection that is opposite to the direction of sheet discharge, so thereare no mis-operations when discharging sheets from the sheet dischargeoutlets 12 b, and 12 c to the trays 11 b and 11 c. Also, the status ofthe stacking of sheets can be precisely detected, so there are nodischarge problems in sheets discharged from the sheet discharge outlets12 b, and 12 c. The plate-shaped member 32 blocks (or protects) sheets(or a bundle) so the movable lever member 14 b is not damaged.Similarly, the second preventing means 17 (17 a and 17 b) prevent damageof the weight member 15 (15 a and 15 b).

Furthermore, with the multi-bin sorter 10 of the present invention,first preventing means 16 and second preventing means 17 are equipped inpairs. Even if sheets (or a bundle) are inserted in the directionopposite to the sheet discharge direction, the projection 34 on theplate-shaped member 32 touches the control portion 35 on the supportmember 33 thereby controlling the rotating movement. Because of theoblique position (see FIGS. 7C and 8C), the leading ends of sheets (orsheet bundle) re-inserted to the trays 11 b or 11 c are guided properlytoward the trays 11 b and 11 c.

With the multi-bin sorter 10, the bottom end of the plate-shaped member32 of the first preventing means 16 is disposed to be positioned abovethe sheet maximum stacking amount detection position (see FIG. 9) wherethe movable lever member 14 b is positioned, using the plane of theobliquely disposed tray 11 as a reference. For that reason, even if thetray 11 is completely filled with sheets, the first preventing means 16,and the plate-shaped member 32 do not interfere with the sheets on thetray. They neither disrupt the alignment of the sheets on the tray, nordamage the sheets on the tray, nor invite sheet discharging problems.Therefore, it is possible to always accurately detect the full loadwhich is the maximum stacking amount of sheets on the tray.

Still further, the weight members 15 and movable lever member 14 areequipped in pairs in the width direction of discharging sheets at thesame discharge outlet for the multi-bin sorter 10 of the presentinvention. Because the weight member 15 and the movable lever members 14act to push discharging sheets downward, they improve the alignment ofsheets discharged to the tray 11. Because the movable lever members 14and the weight members 15 are each fixed to the different shaft 24 andthe shaft 28 independently and freely rotate, it is possible to apply anappropriate amount of pushing force downward toward the tray 11 even forcurls that occur with different sizes at both ends in the sheet widthdirection of the leading end and trailing end of sheets when discharged.

Additionally, the multi-bin sorter 10 according to this embodiment ofthe present invention uses the same members for the first preventingmeans 16, the second preventing means 17, the movable lever members 14 band 14 c, and the weight members 15 b and 15 c, so this translates intoreduced costs because parts control is simplified.

Note that an embodiment of the present invention has been described interms of an example as applied to a multi-function device on the imageforming apparatus 1. However, the invention is not limited to this, andcan be properly applied to a device that outputs sheets formed thereuponwith images and characters. Also, the example describes the maximumamount of sheets stacked on each tray, but the invention is by no meanslimited to that disclosure.

This embodiment of the present invention provides one example of aconfiguration of three bins of tray 11 a, 11 b, and 11 c as the traysfor stacking discharged sheets. However, the invention is not limited tothe number of trays (or bins) described herein. It is also perfectlyacceptable for the tray configuration to be applied to one or two trays.Also, the embodiment provides an example using the same parts for themovable lever members 14 b and 14 c, and the weight members 15 b and 15c. Again the invention is not limited thereto and can use differentshapes for each. The plate-shaped member 32 described in this embodimenthas a freely rotating configuration within a 130° angle, but again thisis not a limitation. This can be set to any desired angle (or rotatingregion). Also, this embodiment provided an example of a protectivestructure of a simple plate shape for the movable lever member 14 a andweight member 15 a, but in the same way as for the function of thefastening member 43, it is also perfectly acceptable to apply aprotective structure of continuous or separate plate shapes to cover themovable lever member 14 a and weight member 15 a.

The present application claims the right of priority based on JapanesePatent Application Nos. 2005-129050 and 2005-129105 each filed Apr. 27,2005, and incorporated by reference herein.

1. A sheet discharge tray for stacking discharged sheets, comprising: adetachable member detachably mounted to a main unit from which thesheets are discharged; and a fastening member, attached to the mainunit, for fastening the detachable member to the main unit.
 2. The sheetdischarge tray according to claim 1, further comprising a staticelectricity discharging member for removing static electricity fromdischarged sheets, said static electricity discharging member beingdisposed at a bottom surface of the fastening member.
 3. The sheetdischarge tray according to claim 1, further comprising a lever sensorcomposed of a rotatable, movable lever member for touching a top surfaceof a discharged sheet, and a sensor member for detecting a dischargesheet stacking amount upon rotation of the movable lever member, whereinthe fastening member is disposed above the lever sensor.
 4. The sheetdischarge tray according to claim 3, further comprising a weight memberfor pushing discharging sheets downward, wherein the fastening member isprovided in a pair with the movable lever member in a width direction ofthe discharged sheets, and disposed above the weight member.
 5. Thesheet discharge tray according to claim 1, wherein the fastening membercomprises, on a bottom surface thereof, a plurality of ribs for guidingdischarged sheets.
 6. The sheet discharge tray according to claim 5,wherein the detachable member comprises a plurality of ribs forconnecting with the plurality of ribs on the fastening member whenmounted to the main unit.
 7. A multi-bin sorter comprising: a pluralityof sheet discharge trays for stacking, in a vertical direction, sheetsdischarged from a sheet discharge outlet of a main unit, with each ofthe trays comprising a detachable member detachably mounted to the mainunit; and a fastening member, attached to the main unit, for fasteningthe detachable member to the main unit.
 8. The multi-bin sorteraccording to claim 7, wherein the fastening member is integrallyprovided with an upright surface of the sheet discharge outlet.
 9. Themulti-bin sorter according to claim 7, wherein the fastening membercomprises, on a bottom surface thereof, a static electricity dischargingmounting member for removing static electricity charged to dischargingsheets, is integral to an upright surface of the sheet discharge outlet,and has a projecting shape for protecting members positioned below, fromabove.
 10. The multi-bin sorter according to claim 7, further comprisinga rotatable, movable lever member provided near the sheet dischargeoutlet for touching a top surface of a sheet stacked on the sheetdischarge tray and rotating thereat; a sensor for detecting a stackingstate of the sheet stacked on the sheet discharge tray upon rotation ofthe movable lever member; and first preventing means provided at a spaceabove the sheet discharge tray at a downstream side in a direction ofsheet discharge of the movable lever member, for preventing insertion ofa sheet above the movable lever member in a direction opposite to thedirection of sheet discharge.
 11. The multi-bin sorter according toclaim 10, wherein the first preventing means has a rotatableplate-shaped member capable of rotating freely within a predeterminedfirst rotatable angle in a first direction rotating by contact with asheet discharged from the sheet discharge outlet, and a second rotatableangle of the plate-shaped member, in a second direction opposite to thefirst direction, is controlled to be smaller than the first rotatableangle, when a sheet contacts the plate-shaped member in a directionopposite to the direction of the sheet discharge.
 12. The multi-binsorter according to claim 10, wherein the first preventing meanscomprises a plate-shaped member with a rotating shaft having aprojection formed on an end thereof, a rotating range of theplate-shaped member being controlled at a predetermined angle, and asupporting member that pivotally supports the rotating shaft, theprojection capable of contacting a portion of an inner wall of a bearingof the support member to control a range of rotation of the plate-shapedmember.
 13. The multi-bin sorter according to claim 12, wherein thesheet discharge tray is obliquely arranged with respect to the mainunit, and a bottom end position of the plate-shaped member is higher,with reference to a plane of the tray, than a sheet stacking amountdetection position at which the movable lever member is positioned whena sheet maximum stacking amount is detected by the sensor.
 14. Themulti-bin sorter according to claim 12, wherein the plate-shaped memberhangs in a substantially vertical posture under its own weight.
 15. Themulti-bin sorter according to claim 14, wherein the plate-shaped memberis arranged to be able, if a sheet is manually inserted in a directionopposite to the direction of sheet discharge and an end of the insertedsheet touches the plate-shaped member, to rotate from the substantiallyvertical posture to the predetermined angle in the second direction suchthat the rotation is controlled and so as to guide the sheet toward thetray.
 16. The multi-bin sorter according to claim 10, wherein the firstpreventing means comprises a support member with a projection providedat an end thereof, and the main unit comprises a concave portionprovided in a wall thereof so that the projection of the support memberis detachably inserted into the concave portion to position the firstpreventing means at a predetermined position.
 17. The multi-bin sorteraccording to claim 10, further comprising a weight member providedrotatably near the sheet discharge outlet and at an opposite side of themovable lever member interposed by the sheet discharge outlet, saidweight member pushing the sheet ejected from the sheet discharge outletdownwardly, and second preventing means provided at a space above thetray at a downstream side in the direction of sheet discharge of theweight member, for preventing insertion of a sheet above the weightmember in a direction opposite to the sheet discharge direction.
 18. Themulti-bin sorter according to claim 17, wherein the movable lever memberand weight member are substantially the same shape, and are provided asa pair in a direction that intersects the sheet discharge direction. 19.The multi-bin sorter according to claim 18, wherein the first and secondpreventing means are substantially the same shape.